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Rediff News  All News  » Getahead » 'Brain pruning': A new theory behind teenage rebellion

'Brain pruning': A new theory behind teenage rebellion

April 07, 2009 12:52 IST

Ever wonder why teenagers are always acting up?

Why they rebel against any form of authority?

Why the slightest provocation can incite a war of words?

Whether its getting crazy tattoos, alcohol abuse, experimenting with drugs, moodiness or indulging in unprotected sex -- the blame is squarely placed on 'raging hormones'. However, a recent study suggests that there may be more to it than just that.

According to report published on website, researchers at the National Institute of Mental Health in Maryland (US) have found that 'brain pruning' may better explain why adolescents act the way they do.

The study tracked the brain development of 400 children every two years and found that about 1 percent of the brain's grey matter was lost every year right into their early 20s. This one percent accounted for the unused neural matter that was overproduced during the child's growing years.

The 'pruning' begins with the areas of the brain responsible for the more basic and motor functions, moves on to the language and spatial regions of the brain and finally the area of the brain responsible for decision-making and impulse control. It is the pruning of the last area that could explain why many teenagers exhibit moodiness, short tempers and indulge in what may be described as bizarre behaviour.

As white matter gradually replaces the lost grey matter, neural connections stabilise and behaviour begins to stabilise as well. The research suggests that while this pruning encourages learning in children, it could also be the reason for increased risk-taking behaviour.